Editing Complement system (section)

=== Complement protein fragment nomenclature ===
Immunology textbooks have used different naming assignments for the smaller and larger fragments of C2 as C2a and C2b. The preferred assignment appears to be that the smaller fragment be designated as C2a: as early as 1994, a well known textbook recommended that the larger fragment of C2 should be designated C2b.<ref name="Janeway1994">{{Cite book |title=Immunobiology: The Immune System in Health and Disease |vauthors=Janeway C, Travers P |date=1994 |publisher=Current Biology Limited, Garland Publishing. Inc. |isbn=0-8153-1691-7 |location=London; San Francisco; New York}}{{page needed|date=May 2015}}</ref> However, this was amplified in their 1999 4th edition, to say that:<ref name="janeway1999">{{Cite book |title=Immunobiology: The Immune System in Health and Disease |vauthors=Janeway CA, Travers P, Walport M, Capra JD |date=1999 |publisher=Garland Publishing, Inc. |isbn=0-8153-3217-3 |edition=4th |location=New York}}{{page needed|date=May 2015}}</ref>
"It is also useful to be aware that the larger active fragment of C2 was originally designated C2a, and is still called that in some texts and research papers. Here, for consistency, we shall call all large fragments of complement '''b''', so the larger fragment of C2 will be designated C2b. In the classical and lectin pathways the C3 convertase enzyme is formed from membrane-bound C4b with C2b."<ref name="janeway1999" />

This nomenclature is used in another literature:<ref name="abbas">{{Cite book |title=Cellular and Molecular Immunology |vauthors=Abbas AK, Lichtman AH |date=May 2015 |publisher=Saunders |isbn=978-0-7216-0008-6 |edition=5th |location=Philadelphia |page=332 |quote=Note that, in older texts, the smaller fragment is often called C2b, and the larger one is called C2a for historical reasons.}}</ref>
The assignment is mixed in the latter literature, though.
Some sources designate the larger and smaller fragments as C2a and C2b respectively<ref name="Peakman">{{Cite book |title=Basic and Clinical Immunology |vauthors=Peakman M, Vergani D |date=1997 |publisher=Churchill Livingstone |isbn=0-443-04672-7 |location=New York}}{{page needed|date=May 2015}}</ref><ref>{{Cite book |title=Fundamental Immunology |date=1999 |publisher=Lippincott-Raven |isbn=0-7817-1412-5 |veditors=Paul WE |edition=4th |location=Philadelphia}}{{page needed|date=May 2015}}</ref><ref name="Sims">{{Cite book |title=Hematology: Basic Principles and Practic |vauthors=Sims PJ, Wiedmer T |date=2000 |publisher=Churchill-Livingstone |isbn=0-443-07954-4 |veditors=Hoffman R, Benz EJ, Shattil SJ, Furie B, Cohen HJ, Silberstein LE, McGlave P |edition=3rd |location=New York; Edinburgh |pages=651–667 |chapter=Complement biology}}</ref><ref>{{Cite book |title=Samter's Immunologic Diseases |vauthors=Frank K, Atkinson JP |date=2001 |publisher=Lippincott Williams & Wilkins |isbn=0-7817-2120-2 |veditors=Austen KF, Frank K, Atkinson JP, Cantor H |edition=6th |volume=1 |location=Philadelphia |pages=281–298 |chapter=Complement system}}</ref><ref name="Roitt">{{Cite book |title=Immunology |vauthors=Roitt I, Brostoff J, Male D |date=2001 |publisher=Mosby |isbn=0-7234-3189-2 |edition=6th |location=St. Louis}}{{page needed|date=May 2015}}</ref><ref name="anderson2003">{{Cite book |title=Dorland's Illustrated Medical Dictionary |vauthors=Anderson DM |date=2003 |publisher=W.B. Saunders |isbn=0-7216-0146-4 |edition=30th |location=Philadelphia}}{{page needed|date=May 2015}}</ref><ref name="Parham">{{Cite book |title=The Immune System |vauthors=Parham P |date=2005 |publisher=Garland |isbn=0-8153-4093-1 |location=New York}}{{page needed|date=May 2015}}</ref><ref name="murphy2008">{{Cite book |title=Janeway's Immunobiology |vauthors=Murphy K, Travers P, Walport M, Ehrenstein M |date=2008 |publisher=Garland Science |isbn=978-0-8153-4123-9 |edition=7th |location=New York}}{{page needed|date=May 2015}}</ref><ref name="Atkinson">{{Cite book |title=Kelley's Textbook of Rheumatology |vauthors=Atkinson JP |date=2009 |publisher=Saunders/Elsevier |isbn=978-1-4160-3285-4 |veditors=Firestein GS, Budd RC, Harris Jr ED, McInnes IB, Ruddy S, Sergent JS |location=Philadelphia, PA |pages=323–336 |chapter=Complement system}}</ref> while other sources apply the converse.<ref name="Janeway1994" /><ref name="janeway1999" /><ref name="Janeway_2001">{{Cite book |url=https://archive.org/details/immunobiology00char |title=Immunobiology |vauthors=Janeway Jr CA, Travers P, Walport M, Shlomchik MJ |publisher=Garland Publishing |year=2001 |isbn=978-0-8153-3642-6 |edition=5th |chapter=The complement system and innate immunity |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK27100/}}</ref><ref name="doan2007">Doan T, Melvold R, Viselli S, Waltenbaugh C (2007). ''Lippincott's Illustrated Reviews: Immunology,'' 320p. Lippincott Williams & Wilkins{{page needed|date=May 2015}}</ref><ref name="DeFranco">{{Cite book |title=Immunity : The Immune Response in Infectious and Inflammatory Disease |vauthors=DeFranco AL, Locksley RM, Robertson M |date=2007 |publisher=New Science Press; Sinauer Associates |isbn=978-0-9539181-0-2 |location=London; Sunderland, MA}}{{page needed|date=May 2015}}</ref> However, due to the widely established convention, C2b here is the larger fragment, which, in the classical pathway, forms C4b2b (classically C4b2a). It may be noteworthy that, in a series of editions of Janeway's book, 1st to 7th, in the latest edition<ref name="murphy2008" /> they withdraw the stance to indicate the larger fragment of C2 as C2b.